SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f2f2c44591dc62e501552820a630345ac6f571deeb82dfd98fff1ff5a9c37634' 
  AND token = '5+knuVKwPQ2j+fjiuohSufeqz6jjNtSRr8MiODsziAY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}